Exporting to 3ds without smoothing
This object is badly designed, imho :) but it surely can be fixed!

I guess it comes from a vector import (cad maybe) but even if blender in solid mode does a decent job of displaying it, this mesh has many flaws. You shouldn't believe me, you should believe the numbers.

Numbers: your model has 70% duplicated verts. A simple "remove doubles" reduces your 38287 verts to 11504!You have 26783 doubles...

But it's not all, imho: in wireframe mode you can even see many weird edges here and there, but to get more numbers, I used the bundled "3d print toolbox", which makes easy to find mesh problems.

Here the result after removing doubles...



Since we know nothing about your "own renderer (OpenGL)" it could be this one to visually show the model weird, probably due to many issues in the model. If you could post a picture of the model in that renderer something could perhaps be guessed...